A teenager murdered a police officer in a "cowardly and merciless act" by running him over in a stolen truck, a court has heard.

Clayton Williams, 19, gave Pc Dave Phillips "no chance" as he struck him in the Mitsubishi 4x4 truck, while the officer was deploying a stinger device to end a high-speed police pursuit, Manchester Crown Court was told.

The 34-year-old officer, a father of two, was tossed into the air before falling, lifeless, on to the road, seconds after the incident in Wallasey, Merseyside, last October. His injuries were not survivable.

Williams, then aged 18, claimed he did not intend to injure or kill the officer and denies a charge of murder.

Pc Phillips' widow Jen sat in the public gallery, yards from Williams in the dock, as the jury of nine women and three men listened to Ian Unsworth QC outlining the case against the defendant.

Grief: Jen Phillips,widow of PC David Phillips, is in the public gallery

The prosecutor said that, in the early hours of October 5 last year, Williams, of Wallasey, and another man, Philip Stuart, 30, of Prenton, Wirral, had burgled a shop in Birkenhead, stealing the keys to the Mitsubishi.

The truck was spotted by an unmarked police vehicle and the officers gave chase, shortly joined by another patrol car, which began recording the pursuit, which will be shown to the jury, on a camera.

Williams drove at "vastly excessive speeds", Mr Unsworth said, along narrow residential roads, through red lights, on the wrong side of the road and struck a parked car during the chase.

Mr Unsworth continued: "All this was done in a determined and ruthless attempt to avoid being apprehended.

"Those same ruthless qualities came to the fore when he approached the police officer who would be killed.

"The officer, Police Constable David Phillips, was doing no more than placing a special device known as a Stop Stick across the road."

"He was simply trying to bring the stolen vehicle to a controlled stop.

"If the defendant had driven over the device, the Stop Stick would then have acted to puncture the tyres and slow the vehicle down."

But instead of driving over the device, Williams drove off the road at his victim, the jury heard.

Mr Unsworth said: "The officer was, as you will see from the film recording, clearly visible, and, we suggest, had been for some distance beforehand.

"As events unfolded he stood little or no chance.

"Pc Phillips moved backwards from where he was. Once the truck was a very short distance from the officer, the defendant turned it sharply to the left."

Shock: Floral tributes at scene where PC Phillips was knocked down in Wallasey, Merseyside (Photo: PA)

"It was, you may think, a cowardly and merciless act. Pc Phillips' fate was sealed."

The officer was hit by the front of the truck and tossed into the air, landing "lifeless" on the road with "catastrophic" injuries, and was pronounced dead a short time later despite efforts to save his life.

"He could not and would not survive his injuries," Mr Unsworth added, as Mrs Phillips sniffled and dabbed her eyes with a tissue.

The barrister told the jury that the manner in which Williams drove the vehicle at the officer showed he had the intention to injure or kill.

After hitting Pc Phillips, he then drove back on to the road in the direction of a second officer, Pc Thomas Birkett, who had to leap out of the way, before Williams fled into the night and took deliberate steps to conceal his involvement, the court heard.

Williams denies a second count of attempted grievous bodily harm with intent to Pc Birkett.

He has admitted the burglary in which the car was stolen and aggravated vehicle taking.